The heart of a computer is a magnetic hard disk drive (HDD) which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing the write and read heads are employed for writing magnetic impressions to and reading magnetic signal fields from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
The volume of information processing in the information age is increasing rapidly. In particular, it is desired that HDDs be able to store more information in their limited area and volume. A technical approach to this desire is to increase the capacity by increasing the recording density of the HDD. To achieve higher recording density, further miniaturization of recording bits is effective, which in turn typically requires the design of smaller and smaller components.
However, the further miniaturization of the various components, particularly, the pitch of magnetic grains, presents its own set of challenges and obstacles in conventional products.
Conventional media has vertical exchange between the cap layer and the layers therebelow. The media also includes strong horizontal exchange between each of the grains, particularly near the cap. Grains tend to form clusters of grains that behave magnetically as a single entity. Thus, the achievable areal density is a function not only of grain size, but of cluster size as well.
Attempts to reduce the grain size in such conventional media result in an almost exponential increase to the horizontal exchange between magnetic grains, and therefore increases the cluster size as well. The increase in cluster size reduces the achievable areal density. As a result, conventional products are unable to reduce the grain pitch and/or the grain size of media without greatly sacrificing storage density thereon.